package design._11_proxy;

import java.io.File;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;

import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
/**
 * 提高系统的扩展性
 * @author nrzt
 *
 */
public class XMLUtil {
	//该方法用于从XML配置文件中提取具体类类名，并返回一个实例对象
	public static Object getBean() {
		try {
			//创建文档对象
			DocumentBuilderFactory dFactory = DocumentBuilderFactory.newInstance();
			DocumentBuilder builder = dFactory.newDocumentBuilder();
			Document doc;
			doc = builder.parse(new File("config.xml"));
			//获取包含类名的文本节点
			NodeList nl = doc.getElementsByTagName("className");
			Node classNode=nl.item(0).getFirstChild();
			String cName=classNode.getNodeValue();
			//通过类名生成实例对象并将其返回
			Class c=Class.forName(cName);
			Object obj=c.newInstance();
			return obj;
		}
		catch(Exception e) {
			e.printStackTrace();
			return null;
		}
	}
}
